Find the value of the unknown exterior angles x in the following diagrams:
(i) It is given in the question that,
1st interior angle = 50o and 2nd interior angle = 70o
Note: According to exterior angle theorem,
The measure of an exterior angle of a triangle is equal to the sum of the measure of the two non-adjacent interior angles of the triangle.
Exterior angle = x
Sum of interior angles = 50o + 70o
Thus, using exterior angle theorem,
x = 50o + 70o
x = 120o
∴ The value of x is 120o
(ii) It is given in the question that,
1st interior angle = 65o and 2nd interior angle = 45o
Note: According to exterior angle theorem,
The measure of an exterior angle of a triangle is equal to the sum of the measure of the two non-adjacent interior angles of the triangle.
Exterior angle = x
Sum of interior angles = 65o + 45o
Using, exterior angle theorem, we have
x = 65o + 45o
x = 110o
Hence, the value of x is 110o
(iii) It is given in the question that,
1st interior angle = 30o and 2nd interior angle = 40o
Note: According to exterior angle theorem,
The measure of an exterior angle of a triangle is equal to the sum of the measure of the two non-adjacent interior angles of the triangle.
Exterior angle = x
Sum of interior angles = 30o + 40o
Using exterior angle theorem, we have
x = 30o + 40o
x = 70o
Hence, the value of x is 70o
(iv) It is given in the question that,
1st interior angle = 60o and 2nd interior angle = 60o
Note: According to exterior angle theorem,
The measure of an exterior angle of a triangle is equal to the sum of the measure of the two non-adjacent interior angles of the triangle.
Exterior angle = x
Sum of interior angles = 60o + 60o
Using exterior angle theorem, we have
x = 60o + 60o
x = 120o
Hence, the value of x is 120o
(v) It is given in the question that,
1st interior angle = 50o and 2nd interior angle = 50o
Note: According to exterior angle theorem:
The measure of an exterior angle of a triangle is equal to the sum of the measure of the two non-adjacent interior angles of the triangle.
Exterior angle = x
Sum of interior angles = 50o + 50o
Using exterior angle theorem, we have
x = 50o + 50o
x = 100o
Hence, the value of x is 100o
(vi) It is given in the question that,
1st interior angle = 30o and 2nd interior angle = 60o
Note: According to exterior angle theorem:
The measure of an exterior angle of a triangle is equal to the sum of the measure of the two non-adjacent interior angles of the triangle.
Exterior angle = x
Sum of interior angles = 30o + 60o
Using, exterior angle theorem, we have
x = 30o + 60o
x = 90o
Hence, the value of x is 120o